In the field of performance vehicles, the advantages of supercharging are well recognized. The addition of several pounds of intake air pressure or boost improves the horsepower and torque output of most internal combustion engines and particularly those used in racing.
An example of a representative supercharger is the system disclosed in the instant inventor's U.S. Pat. No. 5,224,459. Superchargers of this type are belt-driven centrifugal blowers that may be attached to stock engines and are able to boost performance without engine modification.
Under extreme conditions, the limiting factor in the power output is not the volume and pressure of the air which is introduced into the intake manifold on command but the temperature of the intake air. Increase in temperature affects the volumetric efficiency and acts to reduce the number of molecules per liter of intake air, affects the actual mixture, and consequently limits the horsepower output. In addition, higher temperatures of the air/fuel charge during the compression stroke increase the danger of destructive detonation.
In turbocharged internal combustion engines, intercooling and aftercooling are well known. A turbocharger, which is powered by heated exhaust gases, adds heat by conduction through the metal parts to the intake or induction air, in addition to the heat added by compression. Consequently, a variety of different types of intercoolers and aftercoolers have been developed for turbochargers and particularly for compression ignition (diesel) engines. Such cooling arrangements typically are not adaptable to belt-driven centrifugal superchargers.
Attempts have been made in the past to cool the intake air after discharge from non-turbo superchargers before it reaches the intake manifold of the engine. This has been accomplished by employing air-to-air cooling by placing ducting (such as made from heat conducting material) from the supercharger to the intake manifold in an area where the outside passage of air tends to cool the exterior of the duct. Placing cooling fins on metal parts of the supercharger or its ducting is another approach. One further approach has been to add a radiator in the path between outside air flow and the engine compartment, similar to existing engine cooling radiators, and connecting an air to water heat exchanger within the duct from the supercharger to the engine, and providing water-to-air cooling. However, these prior art attempts have not totally fulfilled the need for effective intake air cooling.
Another problem in internal combustion engines is the distribution of intake air to each of the cylinders. This must be as even as possible despite the difference in distance between each cylinder and the air intake source. In the past, addition of most types of superchargers would interrupt or destroy any existing tuning of the intake runners. Addition of an aftercooler in most supercharger installations has not allowed tuning of the intake runners. Intake manifold pressure, flow differences and turbulent airflow tend to adversely affect the power limits achievable within existing engines.
There accordingly remains a need for an effective aftercooler for supercharged internal combustion engines.